A normal voice can be defined as a clear quality; the pitch and loudness appropriate for the person’s age, sex and situation; no effort, pain, strain or fatigue; and fulfils the speaker’s occupational, social, and emotional vocal needs.

The basics of voice production:

• The brain. The brain is the commander of the speech and voice equipment. Laryngeal function is controlled by the central and peripheral nervous system. The brain sends impulses to the various muscles involved in speech and voice production; it integrates information received from our ears and other senses and adjusts our speech program accordingly. It also takes our emotions and goals into account when planning the speech & vocal movements.
• The respiratory system provides the air stream that forms the basis of all voice and speech production. Breathing for speech is different than breathing for life. During speech, we take air in mainly through our mouths, inhalation is shorter and quicker and exhalation is prolonged for speech. The volume of air inhaled for speech is variable, depending on the length and loudness of the upcoming utterance.
• The larynx. The larynx is formed by interlinked cartilages, membranes and ligaments, muscles, and soft tissues. It is involved in voice production and plays a crucial role in respiration, swallowing and in airway protection. The vocal folds abduct to open the glottis for respiration and for the production of voiceless sounds, and adduct to close the glottis for swallowing and for the production of voiced sounds.
• Resonators and articulators. The sound, coming from vocal fold vibration, is modified as it travels through the vocal tract which includes the pharynx, oral cavity, and nasal cavity. Different movements of the articulators change the vocal tract and enhance or dampen certain sounds.